1. Field of the Invention
The subject disclosure relates to systems for automatic fire suppression, and more particularly to an improved system for automatically delivering compressed air foam (CAF) to a hazard area via a fire extinguishing spray nozzle. The systems are also effective for delivering CAF, foam and like substances to cover and control fire in typically difficult to safely and properly access areas.
2. Background of the Related Art
For centuries, man has battled unwanted fires. As technology has developed, the fire fighting techniques have matured from the bucket brigade to highly specialized vehicles, systems and chemicals. However, in many instances such as off-shore drilling platforms, boats, bulldozers and the like, access to water distribution networks or access by firefighting vehicles is not available along with other technical challenges. When a fire is relatively small, use of portable fire extinguishers is common. Further, depending upon the source of the fire, water may not be an appropriate agent for suppression. As such, emergency vehicles and portable extinguishers often deliver foam, non-water solutions, water with chemical additives for additional suppression capability and the like.
Use of portable extinguishers from hand-held versions and larger cart-like versions have been widely used and well understood in the art. For example, U.S. Pat. Nos. 5,881,817 and 6,089,324 to Mahrt, each of which is incorporated herein by reference, disclose a portable fire suppression system using cold compressed air foam. The portable system includes a manifold with a mixing chamber for expanding and accelerating the foam through the manifold by injecting cold compressed air adjacent the manifold inlet and at a 68 degree angle relative to the flow direction.
Technology continues to evolve in the area of fire suppression. Exemplary techniques are illustrated in U.S. Pat. No. 6,328,225 to Crampton (the Crampton patent), U.S. Pat. No. 6,082,463 to Ponte, U.S. Pat. No. 5,441,113 to Pierce, and U.S. Pat. No. 3,441,086 to Barnes, each of which is incorporated herein by reference.
Further, advances in technology are often gained by study and use of hazardous or infectious materials such as carcinogens and active virus cultures. As a result of handling such highly toxic and/or dangerous substances, suppression systems are needed to cover and/or control such substances. Although effective suppressants have been developed, an improved system for delivering these suppressants is needed.
A particularly difficult suppressant to deliver is compressed air foam (CAF). CAF is a mix of a concentrate, air and/water that is generated in a mixing chamber and then distributed by a piping network to nozzles in the hazard area. Prior art systems use a nozzle that is an open type. The nozzles are spaced to provide a uniform distribution of CAF over the entire area. The protected area is required by standards to have a set rate of application of agent or CAF per square foot per minute, in order to ensure fire extinguishment. The quality of the foam is a very important aspect of the ability of the foam to extinguish fires and prevent reflash. Approval authorities have recognized the importance of CAF quality and hold manufactures of CAF systems to specific standards in this regard.
Present fixed spray nozzles have not been able to distribute CAF without destroying the foam quality. The prior art nozzles breakdown the expanded CAF yielding a more liquid state thereby reducing the fire fighting ability of the CAF. Further, prior art nozzles do not produce a uniform distribution with the area near the center of the nozzle being particularly difficult to cover with CAF. Still further, prior art nozzles also fail to deliver desired rate of flow of CAF while maintaining the desired CAF quality and/or spray pattern, if at all.